The present invention relates to surgical fasteners for connecting body tissues, tissue and prostheses, tissue and graft or any combination thereof.
Minimally invasive surgery has allowed physicians to carry out many surgical procedures with less pain and disability than conventional, open surgery. In performing minimally invasive surgery, the surgeon makes a number of small incisions through the body wall to obtain access to the tissues requiring treatment. Typically, a trocar is delivered into the body with a cannula. After the trocar pierces into the body cavity, it is removed and the cannula is left with one end in the body cavity.
When a minimally invasive procedure is done in the abdominal cavity, the retroperitoneal space, or chest, the space in which the operation is performed is more limited, and the exposure to the involved organs is more restricted, than with open surgery. Moreover, in a minimally invasive procedure, the instruments used to assist with the operation are passed into the surgical field through cannulae. When manipulating instruments through cannulae, it is extremely difficult to position tissues in their proper alignment with respect to each other, pass a needle through the tissues, form a knot with the suture material once the tissues are aligned, and prevent the suture material from becoming tangled.
The fastening of body tissues together, or of fastening body tissues to graft materials becomes much more difficult in the restricted spaces imposed upon a surgeon when working through cannulae. Because the use of sutures is often difficult if not impossible in these situations, various other forms of fasteners have been developed to simplify the joining together of tissues and tissues with grafts in these environments, as well as in more conventional surgical procedures.
One variation of a suture is disclosed in U.S. Pat. No. 5,002,563, which forms surgical sutures from shape memory alloys. A suture is formed in the shape of a loop and a needle is affixed to an end thereof. A straight sleeve is provided to maintain the suture relatively straight as it is being inserted into the tissues to be joined. Removal of the sleeve allows the suture to return to its memorized loop shape. End segments of the loop can then be interlocked manually to secure the wound closure. Although this device is less cumbersome than tying conventional sutures, it still requires a coordinated effort to advance the suture into the tissues while removing the sleeve during the insertion process. Also, the interlocking step is similar to suturing, if not as difficult or complicated as tying a conventional suture. This device is disclosed for use in closure of deep wounds and there is no suggestion of use in close environments such as in minimally invasive surgical procedures.
PCT publication nos. WO 99/62406 and WO 99/62409, which are commonly assigned to the assignee of the present application, disclose tissue connector assemblies having a clip movable between an open state and a closed state and a mechanical restraining device attached to the clip for restraining the clip in its open state. The clip has a generally U-shaped configuration when in its open state. A needle may be releasably attached to the clip. This type of tissue connector assembly is discussed further below, with regard to FIGS. 4 and 5. PCT publication nos. WO 99/62406 and WO 99/62409 are incorporated herein, by reference thereto, in their entireties.
The present invention involves surgical fasteners having biasing members which aid in the closure of the fasteners, and methods of making such fasteners. A fastener, according to the present invention, includes a clip movable between an open configuration and a closed configuration, and a biasing member contacting the clip and biased to conform to the closed configuration when in a free state. The biasing member may be applied to form an integrated system with the clip, such that the biasing member and clip actuate in concert to close the fastener, thereby providing an optimal fastener configuration exhibiting an optimal closing force.
Additionally, the clip is biased to conform to the closed configuration when in a free state. The clip may comprise a wire having a shape memory which defines a closed configuration, which may be substantially spiral-shaped, or another shape.
The biasing member may comprise a coil surrounding at least a portion of the clip, and may be a double coil. The biasing member may reside between two restraints located on the clip. Further, a release mechanism may be provided which is adapted to engage the clip at at least one of the restraints and to bias the biasing member to force the clip into the open configuration.
A method of making a surgical fastener according to the present invention includes winding a clip, formed of a shape memory material, into a predetermined closed configuration; setting the clip into the predetermined closed configuration so that the clip has a memory configuration which is the predetermined closed configuration; and conforming a biasing member to the clip in the predetermined closed configuration; setting the clip and biasing member into the predetermined closed configuration to form a fastener comprising the clip and the biasing member wherein each has a memory configuration which is the predetermined closed configuration.
The clip and biasing member may each be set by heating at a predetermined temperature for a predetermined time, and the combination of these components may further be set by heating at a predetermined temperature for a predetermined time.